To characterize the amplitude of dynamic processes in molecules, anisotropic parameters can be measured using solid-state NMR. However, the timescales of motion that lead to such a scaling of the anisotropic interactions are not clear. Using numerical simulations in small spin systems, we could show that mostly the magnitude of the anisotropic interaction determines the range of timescales detected by the scaled anisotropic interaction, and experimental parameters play a very minor role.

Dynamic nuclear polarization requires a waveguide that connects the cold (1–10 K) sample space to the outside. To reduce the heating of the sample, a waveguide is produced from steel which has low thermal conductivity but attenuates the microwaves. Therefore, the inside of the waveguide should be plated with silver to reduce electrical losses. We show a new simple way to electroplate such waveguides with a thin silver layer and show that this improves the experimental performance.

Through the advent of fast magic-angle spinning and high magnetic fields, the spectral resolution of solid-state NMR spectra has recently been greatly improved. To take full advantage of this gain, the magnetic field must be stable over the experiment time of hours or even days. We thus monitor the field by simultaneous acquisition of a frequency reference (SAFR) and use this information to correct multidimensional spectra improving resolution and availability of productive magnet time.

The radio-frequency (rf) field amplitude in solid-state NMR probes changes over the sample volume, i.e. different parts of the sample will experience different nutation frequencies. If the sample is rotated inside the coil as it is typical for magic angle spinning in solid-state NMR, such a position-dependent inhomogeneity leads to an additional time dependence of the rf field amplitude. We show that such time-dependent modulations do not play an important role in many experiments.

Sample rotation around the magic angle averages out the dipolar couplings in homonuclear spin systems in a first-order approximation. However, in higher orders, residual coupling terms remain and lead to a broadening of the spectral lines. We investigate the source of this broadening and the effects on the powder line shape in small spin systems with and without chemical shifts. We show that one can expect different scaling behavior as a function of the spinning frequency for the two cases.